A known method and system are based on the measurement of wheel alignment using electronic and optoelectronic sensors with the necessary stability in the given range of measured parameters that are mounted directly on the wheel. The method is based on the application of electronic and optoelectronic sensor systems that form measuring units mounted on wheels of the vehicle. Measurement results obtained with measuring unit sensors are processed using the microprocessor system. Data from the preprocessing system is transmitted to a personal or industrial computer for final processing and information display. The measurement process is controlled from a computer or directly from wheel sensors. The method ensures simultaneous control of all wheel angles. Measuring units contain a set of Charge-coupled devices (hereinafter—CCD) sensors for measuring angles in horizontal plane (toe-in). Tilt sensors (inclinometers) are used to measure vertical angles in the longitudinal (steering wheel axle caster angle) and transverse (camber angle and steering wheel axle tilt angle) direction. The main disadvantages of the method are: the complexity of measuring units and, as a consequence, a long time required to mount them on the wheels, high power consumption by wheel measuring unit sensors, low impact resistance of sensors, and the requirement to align and center measuring units to the wheels of the vehicle.
Known methods and system are based on the use of computer vision. Measurements are taken by processing measured data obtained with flash light emitters on special targets placed on the wheels of the vehicle and reading radiation pulses reflected from targets with video cameras. Video cameras and emitters are built using CCD technology. Measurement results obtained with video cameras are processed using the microprocessor system. Measurement results are processed and returned using a personal or industrial computer to be installed separately. The main disadvantages of the method are: restrictions on spatial system configuration and sizes of the tested vehicles imposed to ensure target visibility by video cameras.
Another known method and system of determining vehicle wheel alignment based on a gyroscopic sensor is disclosed in U.S. Pat. No. 5,038,485, filed Aug. 13, 1991 (METHOD AND APPARATUS FOR MEASUREMENT OF WHEEL ALIGNMENT). The method and system are based on using one single portable angle measurement instrument which is connected to a stationary unit. The angle measurement instrument includes a gyroscope unit connected to an angle measurement device. By applying the angle measurement instrument subsequently to each of the wheels of the vehicle to be measured, the respective angles between the wheel and a directionally stable axis of the gyroscope unit itself are measured and are stored in memories. Subsequently the desired wheel alignment parameters are calculated by processing the measurement values stored in the memories by means of calculation circuitries and are displayed in the display unit. Reference direction of the gyroscope at first is adjusted at one of the wheels, preferably a rear wheel, at a selected part of the vehicle or the reference basis and then unchanged until the end of the measurement. The main disadvantages of this method are: Use of one gyroscopic measurement unit doesn't offer capability to see the mutual alignment angle changing in the case of wheel adjustment. Total wheel alignment measurement in this case, further taking into account each wheel's curve compensation, is a long, complicated procedure that requires a precise and complex sequence of actions and thus is not capable of adjustment of wheel angles or real time alignment tracking.
Yet another known method and system of determining vehicle wheel alignment based on a gyroscopic sensor is disclosed in U.S. Pat. No. 7,089,150 B2 and U.S. Pat. No. 7,324,916. The method and system are based on the measurement of the wheel alignment, using gyroscopic sensors based on calculating changes in the angles from an initial surface located on the vehicle. The system includes a gyro sensor, which can be rigidly connected with inclinometers on two orthogonal axes, as well as an electronic computer system and interface with the operator. It assumes an initial vehicle measurement point with a known position relative to the vehicle wheels. In general, during the initialization of the reference point, tilt sensors (inclinometers) are set to zero, or the computer system compensates for further measurements when calculating the slope of the gyroscopic sensor. In general, after initialization, it is suggested to install the sensor on the measured wheel, and obtain the value of the angles of the wheels by calculating the change of angles relative to the initial position. The main disadvantages of this method are: the lack of publicly available vehicle control points data, which could serve as data for starting points for measurement; not all vehicles can be used for measuring the control points, because they are not available without additional work to dismantle parts of the vehicle; the complexity of regulating wheel alignment with one sensor, taking in account each wheel's curve compensation, the reason being that the angles of the wheels are dependent and quick and accurate regulation requires constant monitoring of the angle values at the axle of the vehicle. It must also be noted that the patent's conclusions on the calculation of the individual wheel alignments are incorrect. This system can only measure total alignment using two sensors on the axle after their initialization at one control point or after the measurement of both wheels with one sensor sequentially, as at the initialization at the control point, there is not a defined line for the gyroscopic sensor with respect to which the toe is regulated.